Sex steroid hormones in depressive disorders as a basis for new potential treatment strategies.

The sex steroid hormones (SSHs) such as testosterone, estradiol, progesterone, and their metabolites have important organizational and activational impacts on the brain during critical periods of brain development and in adulthood. A variety of slow and rapid mechanisms mediate both organizational and activational processes via intracellular or membrane receptors for SSHs. Physiological concentrations and distribution of SSHs in the brain result in normal brain development. Nevertheless, dysregulation of hormonal equilibrium may result in several mood disorders, including depressive disorders, later in adolescence or adulthood. Gender differences in cognitive abilities, emotions as well as the 2-3 times higher prevalence of depressive disorders in females, were already described. This implies that SSHs may play a role in the development of depressive disorders. In this review, we discuss preclinical and clinical studies linked to SSHs and development of depressive disorders. Our secondary aim includes a review of up-to-date knowledge about molecular mechanisms in the pathogenesis of depressive disorders. Understanding these molecular mechanisms might lead to significant treatment adjustments for patients with depressive disorders and to an amelioration of clinical outcomes for these patients. Nevertheless, the impact of SSHs on the brain in the context of the development of depressive disorders, progression, and treatment responsiveness is complex in nature, and depends upon several factors in concert such as gender, age, comorbidities, and general health conditions.

Sex Difference in Plasma Deoxyribonuclease Activity in Rats.

Extracellular DNA (ecDNA) activates immune cells and is involved in the pathogenesis of diseases associated with inflammation such as sepsis, rheumatoid arthritis or metabolic syndrome. DNA can be cleaved by deoxyribonucleases (DNases), some of which are secreted out of cells. The aim of this experiment was to describe plasma DNase activity in relation to extracellular DNA in adult rats, to analyse potential sex differences and to prove whether they are related to endogenous testosterone. Adult Lewis rats (n=28) of both sexes were included in the experiment. Male rats were gonadectomized or sham-operated and compared to intact female rats. Plasma ecDNA and DNase activity were measured using fluorometry and single radial enzyme diffusion assay, respectively. Concentrations of nuclear ecDNA and mitochondrial ecDNA were determined using real-time PCR. Females had 60% higher plasma DNase activity than males ( p=0.03). Gonadectomy did not affect plasma DNase in males. Neither the concentration of total ecDNA, nor nuclear or mitochondrial DNA in plasma differed between the groups. No significant correlations between DNase and ecDNA were found. From previous studies on mice, it was expected, that male rats will have higher DNase activity. In contrast, our study in rats showed the opposite sex difference. This sex difference seems not to be caused by endogenous testosterone. Interestingly, no sex differences were observed in plasma ecDNA suggesting a complex or missing association between plasma ecDNA and DNase. The observed sex difference in plasma DNase should be taken into account in animal models of ecDNA-associated diseases.

Acute effect of cola and caffeine on locomotor activity in drosophila and rat.

Caffeine is well known for reducing fatigue and its effect on behavior is widely studied. Usually, caffeine is not ingested in its pure form but rather in sugar-sweetened beverages such as cola. Our aim was to compare the acute effect of cola and caffeine on locomotor activity. Rats and flies ingested cola or caffeine solution for 24 hours. The open field test revealed higher locomotor activity in cola groups for both flies and rats. Surprisingly, no differences have been observed between caffeineand control group. We conclude that caffeine itself does not explain the effect of cola on locomotor activity. Effect of cola cannot be generalized and interpreted for any caffeinated drink with other contents. Rather, the observed effect on locomotor activity may be caused by interaction of caffeine with other substances present in cola.

The effect of long-term hypogonadism on body composition and morphometry of aged male Wistar rats.

Clinical studies show that hypogonadism in the aging male is associated with obesity and osteoporosis. Experimental studies are mostly conducted on relatively young adult animals and the induced hypogonadism lasts for a relatively short time. The present study aimed to describe the effect of long-term hypogonadism beginning in puberty on body composition, morphometry, and bone mineral density in aged male rats. Morphometric measurements and dual-energy X-ray absorptiometry were conducted at the age of 30 months on control and gonadectomized males. Long-term hypogonadism did not affect body weight, but led to a higher fat mass (by 26 %), lower lean mass (by 44 %), shorter body length (by 9 %), and anogenital distance (by 26 %), as well as to lower tail circumference (by 15 %) in comparison to control males. Lower bone mineral density (by 13 %) and bone mineral content (by 15 %) were observed in gonadectomized males. Results showing sarcopenic obesity and osteoporosis in this model of long-term hypogonadism might mimic the situation in aging males better than the widely used short-term hypogonadism induced in young animals. The morphometric analysis could potentially be a useful tool to study normal weight obesity without the need for specific equipment.

Neonatal hypoxic-ischemic brain injury leads to sex-specific deficits in rearing and climbing in adult mice.

The study examined the morphological and long-term behavioral impacts of neonatal hypoxic-ischemic brain injury in a mouse model. We investigated the modification of different behavioral domains, such as spontaneous climbing, which represents fine motor skills. We also focused on sex-dependent differences during hypoxic-ischemic encephalopathy. The Rice-Vannucci model of hypoxia-ischemia was used, adjusted and adapted to 7-day-old C57BL/6NTac mice. The effects of induced hypoxia and ischemia were also studied separately. At postnatal day 60, mice underwent behavioral testing using the LABORAS apparatus. The perfusion for histological evaluation was performed one day after the behavioral analyses. In groups with separately induced hypoxia or ischemia, the observed alterations in behavior were not accompanied by morphological changes in the cortex or hippocampal formation. Female mice naturally climbed significantly more and hypoxic females reared less than hypoxic males (p<0.05). Male mice postnatally exposed to hypoxia-ischemia exhibited significantly lower vertical activity and higher horizontal activity (p<0.05). Mild hypoxic damage may not be morphologically detectable but may induce substantial behavioral changes in adult mice. There were significant differences between horizontal and vertical activity in reaction to hypoxia-ischemia. Our study indicates that the importance of behavioral testing is irreplaceable and may be reflected in neonatal medicine.

Perinatal hypoxic-ischemic damage: review of the current treatment possibilities.

Neonatal hypoxic-ischemic encephalopathy is a disorder with heterogeneous manifestation due to asphyxia during perinatal period. It affects approximately 3-12 children per 1000 live births and cause death of 1 million neonates worldwide per year. Besides, motor disabilities, seizures, impaired muscle tone and epilepsy are few of the consequences of hypoxic-ischemic encephalopathy. Despite an extensive research effort regarding various treatment strategies, therapeutic hypothermia with intensive care unit supportive treatment remains the only approved method for neonates who have suffered from moderate to severe hypoxic-ischemic encephalopathy. However, these protocols are only partially effective given that many infants still suffer from severe brain damage. Thus, further research to systematically test promising neuroprotective treatments in combination with hypothermia is essential. In this review, we discussed the pathophysiology of hypoxic-ischemic encephalopathy and delved into different promising treatment modalities, such as melatonin and erythropoietin. However, preclinical studies and clinical trials are still needed to further elucidate the mechanisms of action of these modalities.

Early postnatal hypoxia induces behavioral deficits but not morphological damage in the hippocampus in adolescent rats.

Hypoxia is one of the major pathological factors affecting brain function. The aim of the present study was to describe the effect of neonatal hypobaric hypoxia on the behavior of rats and to analyze its effect on hippocampal neurodegeneration. Hypobaric hypoxia at a simulated altitude of 9000 m was induced for one hour in neonatal rat pups (PND7 and PND9) of both sexes. Subsequently, the rats underwent behavioral testing on PND25 and PND35 using a LABORAS apparatus to assess spontaneous behavior. Hypoxia did not cause any morphological damage in the hippocampus of rats. However, hypoxia on PND7 led to less horizontal locomotor activity both, in males (on PND25) and females (on PND35). Hypoxia on PND9 led to higher rearing in females on PND25. Hypoxic males exhibited higher grooming activity, while females lower grooming activity on PND35 following hypoxia induced on PND7. In females, hypoxia on PND9 resulted in higher grooming activity on PND25. Sex differences in the effect of hypoxia was observed on PND35, when hypoxic males compared to hypoxic females displayed more locomotor, rearing and grooming activity. Our data suggest that hypoxia on PND7 versus PND9 differentially affects locomotion and grooming later in adolescence and these effects are sex-dependent.

Does the 2nd and 4th digit ratio reflect prenatal androgen exposure?

OBJECTIVES:  The aim of our study was to describe the effect of prenatal testosterone exposure on 2D:4D in both sexes, and to determine whether this effect is mediated via the androgen receptor. In addition, the sex differences in lengths of 2D, 4D, and 2D:4D ratio were analyzed. BACKGROUND:  Clinical studies suggest a negative correlation between prenatal testosterone exposure and ratio of the lengths of the second and fourth digits (2D:4D). However, less is known about the underlying molecular mechanisms. METHODS:  Pregnant rats were treated with olive oil, testosterone, flutamide or testosterone with flutamide daily from the fourteenth day of pregnancy until delivery. The finger lengths of adult offspring were measured using both, digital scanning of the paws and µCT analysis of the phalanges. RESULTS:  None of the aforementioned methods revealed any effect of testosterone on 2D:4D. µCT measurements showed that prenatal hyperandrogenism in both sexes leads to shorter 2D compared to controls. Moreover, the testosterone treatment in males resulted in the shortening of 4D when compared to controls. CONCLUSION:  Prenatal hyperandrogenism leads to shorter lengths of 2D and 4D; however, it does not affect 2D:4D ratio. Whether other steroid hormones and/or testosterone metabolites affect the 2D:4D ratio requires further investigation (Tab. 5, Fig. 3, Ref. 32).

Gender differences involved in the pathophysiology of the perinatal hypoxic-ischemic damage.

Hypoxic-ischemic encephalopathy (HIE) is a neonatal condition that occurs as a consequence of perinatal asphyxia, which is caused by a number of factors, commonly via compression of the umbilical cord, placental abruption, severe meconium aspiration, congenital cardiac or pulmonary anomalies and birth trauma. Experimental studies have confirmed that male rat pups show a higher resistance to HIE treatment. Moreover, the long-term consequences of hypoxia in male are more severe in comparison to female rat pups. These sex differences can be attributed to the pathophysiology of hypoxia-ischemia, whereby studies are beginning to establish such gender-specific distinctions. The current and sole treatment for HIE is hypothermia, in which a reduction in temperature prevents long-term effects, such as cerebral palsy or seizures. However, in most cases hypothermia is not a sufficient treatment as indicated by a high mortality rate. In the present review, we discuss the gender differences within the pathophysiology of hypoxia-ischemia and delve into the role of gender in the incidence, progression and severity of the disease. Furthermore, this may result in the development of potential novel treatment approaches for targeting and preventing the long-term consequences of HIE.

Sex-related differences in locomotion and climbing of C57Bl/6NTac mice in a novel environment.

Laboratory mice in standard laboratory cages, besides horizontal and vertical locomotor activity, spontaneously display cage-bar related activities such as cage-grid climbing. Although, grid-climbing activity is one of the major components of spontaneous home-cage behavior of mice, its exact role is not fully understood. This study aimed to describe the sex-differences in coping with novelty and in spontaneous behavior of laboratory mice concerning the cage-climbing activity in an observer-independent open field test. Adult mice of both sexes (C57Bl/6NTac) underwent behavioral testing in LABORAS system. Female mice travelled significantly longer distance (by 30 %, p<0.05) and showed higher grid-climbing activity (by 50 %, p<0.05) than males. Based on our results, the grid-climbing is a sex-dependent activity of mice, however, its exact role remains to be elucidated.

Sex differences in the effect of prenatal testosterone exposure on steroid hormone production in adult rats.

Maternal hyperandrogenism during pregnancy might have metabolic and endocrine consequences on the offspring as shown for the polycystic ovary syndrome. Despite numerous experiments, the impact of prenatal hyperandrogenic environment on postnatal sex steroid milieu is not yet clear. In this study, we investigated the effect of prenatal testosterone excess on postnatal concentrations of luteinizing hormone, corticosterone and steroid hormones including testosterone, pregnenolone, progesterone, estradiol and 7beta-hydroxy-epiandrosterone in the offspring of both sexes. Pregnant rats were injected daily with either testosterone propionate or vehicle from gestational day 14 until parturition. The hormones were evaluated in plasma of the adult offspring. As expected, females had lower testosterone and higher pregnenolone, progesterone and estradiol in comparison to males. In addition, corticosterone was higher in females than in males, and it was further elevated by prenatal testosterone treatment. In males, prenatal testosterone exposure resulted in higher 7beta-hydroxy-epiandrosterone in comparison to control group. None of the other analyzed hormones were affected by prenatal testosterone. In conclusion, our results did not show major effects on sex hormone production or luteinizing hormone release in adult rats resulting from testosterone excess during their fetal development. However, maternal hyperandrogenism seems to partially affect steroid biosynthesis in sex-specific manner.

Effect of Fractionated Irradiation on the Hippocampus in an Experimental Model.

BACKGROUND: Ionizing radiation induces altered brain tissue homeostasis and can lead to morphological and functional deficits. The aim of the present study was to investigate the short-term and long-term effect of ionizing radiation on cell population resides adult rat hippocampus. MATERIALS AND METHODS: Adult male Wistar rats received whole- brain irradiation with fractionated doses of gamma rays (a total dose of 20 Gy) and were investigated 30 and 100 days later. A combination of Fluoro-Jade C histochemistry for visualization of degenerating neurons, immunohistochemistry for detection of astrocytes and confocal microscopy were used to quantify the neurodegenerative changes in the hippocampal dentate gyrus and CA1 subfield. RESULTS: A significant increase of Fluoro-Jade C labelled neurons was seen in both of investigated areas through the whole experiment, predominantly 30 days after irradiation. Non- significant decrease of GFAP- immunoreactive astrocytes was found in the hippocampal dentate gyrus and CA1 subfield until 100 days after irradiation. CONCLUSION: Our recent results showed that radiation response of cell types resides the adult hippocampus may play contributory role in the development of adverse radiation-induced late effects.

Does rat fetal DNA induce preeclampsia in pregnant rats?

Cell-free fetal DNA in maternal circulation is higher during preeclampsia. It is unclear whether it is the cause or the consequence of the disease. The aim of this study was to prove whether injected rat fetal DNA induces preeclampsia-like symptoms in pregnant Wistar rats. They received daily i.p. injections of water or rat fetal DNA (400 µg) from gestation day 14 to 18. Blood pressure, proteinuria, placental and fetal weight were measured at gestation day 19. Plasma DNase activity, proteinuria and creatinine clearance were assessed. There was no significant difference in any of the measured parameters. The results of this study do not confirm the hypothesis that fetal DNA might induce preeclampsia. This is in contrast to others using human fetal DNA in mice. Further studies should be focused on the effects of fetal DNA from the same species protected from DNase activity.